FreeBSD-5.3/sys/vm/uma_int.h
/*
* Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice unmodified, this list of conditions, and the following
* disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD: src/sys/vm/uma_int.h,v 1.25 2004/07/29 15:25:40 bmilekic Exp $
*
*/
/*
* This file includes definitions, structures, prototypes, and inlines that
* should not be used outside of the actual implementation of UMA.
*/
/*
* Here's a quick description of the relationship between the objects:
*
* Kegs contain lists of slabs which are stored in either the full bin, empty
* bin, or partially allocated bin, to reduce fragmentation. They also contain
* the user supplied value for size, which is adjusted for alignment purposes
* and rsize is the result of that. The Keg also stores information for
* managing a hash of page addresses that maps pages to uma_slab_t structures
* for pages that don't have embedded uma_slab_t's.
*
* The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
* be allocated off the page from a special slab zone. The free list within a
* slab is managed with a linked list of indexes, which are 8 bit values. If
* UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit
* values. Currently on alpha you can get 250 or so 32 byte items and on x86
* you can get 250 or so 16byte items. For item sizes that would yield more
* than 10% memory waste we potentially allocate a separate uma_slab_t if this
* will improve the number of items per slab that will fit.
*
* Other potential space optimizations are storing the 8bit of linkage in space
* wasted between items due to alignment problems. This may yield a much better
* memory footprint for certain sizes of objects. Another alternative is to
* increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes. I prefer
* dynamic slab sizes because we could stick with 8 bit indexes and only use
* large slab sizes for zones with a lot of waste per slab. This may create
* ineffeciencies in the vm subsystem due to fragmentation in the address space.
*
* The only really gross cases, with regards to memory waste, are for those
* items that are just over half the page size. You can get nearly 50% waste,
* so you fall back to the memory footprint of the power of two allocator. I
* have looked at memory allocation sizes on many of the machines available to
* me, and there does not seem to be an abundance of allocations at this range
* so at this time it may not make sense to optimize for it. This can, of
* course, be solved with dynamic slab sizes.
*
* Kegs may serve multiple Zones but by far most of the time they only serve
* one. When a Zone is created, a Keg is allocated and setup for it. While
* the backing Keg stores slabs, the Zone caches Buckets of items allocated
* from the slabs. Each Zone is equipped with an init/fini and ctor/dtor
* pair, as well as with its own set of small per-CPU caches, layered above
* the Zone's general Bucket cache.
*
* The PCPU caches are protected by their own locks, while the Zones backed
* by the same Keg all share a common Keg lock (to coalesce contention on
* the backing slabs). The backing Keg typically only serves one Zone but
* in the case of multiple Zones, one of the Zones is considered the
* Master Zone and all Zone-related stats from the Keg are done in the
* Master Zone. For an example of a Multi-Zone setup, refer to the
* Mbuf allocation code.
*/
/*
* This is the representation for normal (Non OFFPAGE slab)
*
* i == item
* s == slab pointer
*
* <---------------- Page (UMA_SLAB_SIZE) ------------------>
* ___________________________________________________________
* | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________ |
* ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header||
* ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________||
* |___________________________________________________________|
*
*
* This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE.
*
* ___________________________________________________________
* | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
* ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |
* ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |
* |___________________________________________________________|
* ___________ ^
* |slab header| |
* |___________|---*
*
*/
#ifndef VM_UMA_INT_H
#define VM_UMA_INT_H
#define UMA_SLAB_SIZE PAGE_SIZE /* How big are our slabs? */
#define UMA_SLAB_MASK (PAGE_SIZE - 1) /* Mask to get back to the page */
#define UMA_SLAB_SHIFT PAGE_SHIFT /* Number of bits PAGE_MASK */
#define UMA_BOOT_PAGES 40 /* Pages allocated for startup */
/* Max waste before going to off page slab management */
#define UMA_MAX_WASTE (UMA_SLAB_SIZE / 10)
/*
* I doubt there will be many cases where this is exceeded. This is the initial
* size of the hash table for uma_slabs that are managed off page. This hash
* does expand by powers of two. Currently it doesn't get smaller.
*/
#define UMA_HASH_SIZE_INIT 32
/*
* I should investigate other hashing algorithms. This should yield a low
* number of collisions if the pages are relatively contiguous.
*
* This is the same algorithm that most processor caches use.
*
* I'm shifting and masking instead of % because it should be faster.
*/
#define UMA_HASH(h, s) ((((unsigned long)s) >> UMA_SLAB_SHIFT) & \
(h)->uh_hashmask)
#define UMA_HASH_INSERT(h, s, mem) \
SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h), \
(mem))], (s), us_hlink);
#define UMA_HASH_REMOVE(h, s, mem) \
SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h), \
(mem))], (s), uma_slab, us_hlink);
/* Hash table for freed address -> slab translation */
SLIST_HEAD(slabhead, uma_slab);
struct uma_hash {
struct slabhead *uh_slab_hash; /* Hash table for slabs */
int uh_hashsize; /* Current size of the hash table */
int uh_hashmask; /* Mask used during hashing */
};
/*
* Structures for per cpu queues.
*/
struct uma_bucket {
LIST_ENTRY(uma_bucket) ub_link; /* Link into the zone */
int16_t ub_cnt; /* Count of free items. */
int16_t ub_entries; /* Max items. */
void *ub_bucket[]; /* actual allocation storage */
};
typedef struct uma_bucket * uma_bucket_t;
struct uma_cache {
uma_bucket_t uc_freebucket; /* Bucket we're freeing to */
uma_bucket_t uc_allocbucket; /* Bucket to allocate from */
u_int64_t uc_allocs; /* Count of allocations */
};
typedef struct uma_cache * uma_cache_t;
/*
* Keg management structure
*
* TODO: Optimize for cache line size
*
*/
struct uma_keg {
LIST_ENTRY(uma_keg) uk_link; /* List of all kegs */
struct mtx uk_lock; /* Lock for the keg */
struct uma_hash uk_hash;
LIST_HEAD(,uma_zone) uk_zones; /* Keg's zones */
LIST_HEAD(,uma_slab) uk_part_slab; /* partially allocated slabs */
LIST_HEAD(,uma_slab) uk_free_slab; /* empty slab list */
LIST_HEAD(,uma_slab) uk_full_slab; /* full slabs */
u_int32_t uk_recurse; /* Allocation recursion count */
u_int32_t uk_align; /* Alignment mask */
u_int32_t uk_pages; /* Total page count */
u_int32_t uk_free; /* Count of items free in slabs */
u_int32_t uk_size; /* Requested size of each item */
u_int32_t uk_rsize; /* Real size of each item */
u_int32_t uk_maxpages; /* Maximum number of pages to alloc */
uma_init uk_init; /* Keg's init routine */
uma_fini uk_fini; /* Keg's fini routine */
uma_alloc uk_allocf; /* Allocation function */
uma_free uk_freef; /* Free routine */
struct vm_object *uk_obj; /* Zone specific object */
vm_offset_t uk_kva; /* Base kva for zones with objs */
uma_zone_t uk_slabzone; /* Slab zone backing us, if OFFPAGE */
u_int16_t uk_pgoff; /* Offset to uma_slab struct */
u_int16_t uk_ppera; /* pages per allocation from backend */
u_int16_t uk_ipers; /* Items per slab */
u_int16_t uk_flags; /* Internal flags */
};
/* Simpler reference to uma_keg for internal use. */
typedef struct uma_keg * uma_keg_t;
/* Page management structure */
/* Sorry for the union, but space efficiency is important */
struct uma_slab_head {
uma_keg_t us_keg; /* Keg we live in */
union {
LIST_ENTRY(uma_slab) _us_link; /* slabs in zone */
unsigned long _us_size; /* Size of allocation */
} us_type;
SLIST_ENTRY(uma_slab) us_hlink; /* Link for hash table */
u_int8_t *us_data; /* First item */
u_int8_t us_flags; /* Page flags see uma.h */
u_int8_t us_freecount; /* How many are free? */
u_int8_t us_firstfree; /* First free item index */
};
/* The standard slab structure */
struct uma_slab {
struct uma_slab_head us_head; /* slab header data */
struct {
u_int8_t us_item;
} us_freelist[1]; /* actual number bigger */
};
/*
* The slab structure for UMA_ZONE_REFCNT zones for whose items we
* maintain reference counters in the slab for.
*/
struct uma_slab_refcnt {
struct uma_slab_head us_head; /* slab header data */
struct {
u_int8_t us_item;
u_int32_t us_refcnt;
} us_freelist[1]; /* actual number bigger */
};
#define us_keg us_head.us_keg
#define us_link us_head.us_type._us_link
#define us_size us_head.us_type._us_size
#define us_hlink us_head.us_hlink
#define us_data us_head.us_data
#define us_flags us_head.us_flags
#define us_freecount us_head.us_freecount
#define us_firstfree us_head.us_firstfree
typedef struct uma_slab * uma_slab_t;
typedef struct uma_slab_refcnt * uma_slabrefcnt_t;
/*
* These give us the size of one free item reference within our corresponding
* uma_slab structures, so that our calculations during zone setup are correct
* regardless of what the compiler decides to do with padding the structure
* arrays within uma_slab.
*/
#define UMA_FRITM_SZ (sizeof(struct uma_slab) - sizeof(struct uma_slab_head))
#define UMA_FRITMREF_SZ (sizeof(struct uma_slab_refcnt) - \
sizeof(struct uma_slab_head))
/*
* Zone management structure
*
* TODO: Optimize for cache line size
*
*/
struct uma_zone {
char *uz_name; /* Text name of the zone */
struct mtx *uz_lock; /* Lock for the zone (keg's lock) */
uma_keg_t uz_keg; /* Our underlying Keg */
LIST_ENTRY(uma_zone) uz_link; /* List of all zones in keg */
LIST_HEAD(,uma_bucket) uz_full_bucket; /* full buckets */
LIST_HEAD(,uma_bucket) uz_free_bucket; /* Buckets for frees */
uma_ctor uz_ctor; /* Constructor for each allocation */
uma_dtor uz_dtor; /* Destructor */
uma_init uz_init; /* Initializer for each item */
uma_fini uz_fini; /* Discards memory */
u_int64_t uz_allocs; /* Total number of allocations */
uint16_t uz_fills; /* Outstanding bucket fills */
uint16_t uz_count; /* Highest value ub_ptr can have */
/*
* This HAS to be the last item because we adjust the zone size
* based on NCPU and then allocate the space for the zones.
*/
struct uma_cache uz_cpu[1]; /* Per cpu caches */
};
/*
* These flags must not overlap with the UMA_ZONE flags specified in uma.h.
*/
#define UMA_ZFLAG_PRIVALLOC 0x1000 /* Use uz_allocf. */
#define UMA_ZFLAG_INTERNAL 0x2000 /* No offpage no PCPU. */
#define UMA_ZFLAG_FULL 0x4000 /* Reached uz_maxpages */
#define UMA_ZFLAG_CACHEONLY 0x8000 /* Don't ask VM for buckets. */
/* Internal prototypes */
static __inline uma_slab_t hash_sfind(struct uma_hash *hash, u_int8_t *data);
void *uma_large_malloc(int size, int wait);
void uma_large_free(uma_slab_t slab);
/* Lock Macros */
#define ZONE_LOCK_INIT(z, lc) \
do { \
if ((lc)) \
mtx_init((z)->uz_lock, (z)->uz_name, \
(z)->uz_name, MTX_DEF | MTX_DUPOK); \
else \
mtx_init((z)->uz_lock, (z)->uz_name, \
"UMA zone", MTX_DEF | MTX_DUPOK); \
} while (0)
#define ZONE_LOCK_FINI(z) mtx_destroy((z)->uz_lock)
#define ZONE_LOCK(z) mtx_lock((z)->uz_lock)
#define ZONE_UNLOCK(z) mtx_unlock((z)->uz_lock)
#define CPU_LOCK_INIT(cpu) \
mtx_init(&uma_pcpu_mtx[(cpu)], "UMA pcpu", "UMA pcpu", \
MTX_DEF | MTX_DUPOK)
#define CPU_LOCK(cpu) \
mtx_lock(&uma_pcpu_mtx[(cpu)])
#define CPU_UNLOCK(cpu) \
mtx_unlock(&uma_pcpu_mtx[(cpu)])
/*
* Find a slab within a hash table. This is used for OFFPAGE zones to lookup
* the slab structure.
*
* Arguments:
* hash The hash table to search.
* data The base page of the item.
*
* Returns:
* A pointer to a slab if successful, else NULL.
*/
static __inline uma_slab_t
hash_sfind(struct uma_hash *hash, u_int8_t *data)
{
uma_slab_t slab;
int hval;
hval = UMA_HASH(hash, data);
SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) {
if ((u_int8_t *)slab->us_data == data)
return (slab);
}
return (NULL);
}
static __inline uma_slab_t
vtoslab(vm_offset_t va)
{
vm_page_t p;
uma_slab_t slab;
p = PHYS_TO_VM_PAGE(pmap_kextract(va));
slab = (uma_slab_t )p->object;
if (p->flags & PG_SLAB)
return (slab);
else
return (NULL);
}
static __inline void
vsetslab(vm_offset_t va, uma_slab_t slab)
{
vm_page_t p;
p = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)va));
p->object = (vm_object_t)slab;
p->flags |= PG_SLAB;
}
static __inline void
vsetobj(vm_offset_t va, vm_object_t obj)
{
vm_page_t p;
p = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)va));
p->object = obj;
p->flags &= ~PG_SLAB;
}
/*
* The following two functions may be defined by architecture specific code
* if they can provide more effecient allocation functions. This is useful
* for using direct mapped addresses.
*/
void *uma_small_alloc(uma_zone_t zone, int bytes, u_int8_t *pflag, int wait);
void uma_small_free(void *mem, int size, u_int8_t flags);
#endif /* VM_UMA_INT_H */